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Calvin cycle nadph supplies h e s

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Unformatted text preview: Chloroplast Fig. 10- 5- 4 O2 [CH2O] (sugar) Glucose is produced 3 10.2: Light reacGons: solar → chem. energy; “Photo” •  Begins w/ absorpGon of energy by chloroplasts –  Visible light travels in packets (photons) at diff. wavelengths –  Pigments capture most of visible light spectrum, use it to energize e- ’s Light Chloroplast Reflected light Absorbed Granum light Transmiged light Compare to Fig. 10-6 ↑ Green light reflected Important Pigments in Plants •  Main pigment: chlorophyll a; absorbs •  Accessory: chlorophyll b, carotenoids [revealed in fall- photosyn. stops]; protect & pass energy to it •  Photons absorbed, boost e- ’s energy level •  Normally lost as heat; instead, passed to primary e- acceptor Figs. 10.9, 10.10 Animation: Light and Pigments Photosystem: complex of proteins w/in thylakoid membrane • convert light energy into energized e- ’s [hot potato] • enzyme complex that accepts energized e- ’s (reacGon- center complex) Photosystem Photon STROMA Light- harvesGng ReacGon- center Primary electron complex complexes acceptor Thylakoid membrane • Pigments iniGally absorb, transfer energy from photons to e- ’s (light- harvesGng complexes), passed to a e– Transfer of energy Fig. 10- 12 Special pair of chlorophyll a molecules Pigment molecules THYLAKOID SPACE (INTERIOR OF THYLAKOID) 4 Energized e- ’s flow thru an electron transport chain (ETC) •  Passed among proteins in thylakoid membrane •  Pathway ulGmately produces ATP and NADPH for Calvin cycle •  How? Each produced separately, both use energy of e- ’s –  H + concentraGon gradient produces ATP –  NADP + accepts e- ’s and H + •  H + ions into thylakoid, creates concentraJon gradient (inside pH 5> outside pH 8), drives ATP producGon in process named chemiosmosis LIGHT- HARVESTING COMPLEX Compare fig. 10.17 sunlight PHOTOSYSTEM II PHOTOSYSTEM I H+ Thylakoid compartment NADPH e- e- H2O e- O2 e- e- e- e- NADP + + H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ thylakoid membrane cross- secGon through a disk- shaped fold in the thylakoid membrane ATP ADP + Pi stroma H+ Most ATP synthesis in cells occurs by chemiosmosis (is this simple diffusion, facilitated diffusion or acGve transport?) 5 H+ ion concentraGon gradient drives ATP formaGon •  ATP...
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